CLL-211 Humoral Immune Response Following COVID-19 Vaccination in Patients With Chronic Lymphocytic Leukemia (CLL) and Indolent Non-Hodgkin Lymphoma (NHL): Results From a Large, Single-Center Observational Study

Context: CLL and indolent NHL are hematologic malignancies that typically result in immune dysfunction. Infection represents a major cause of morbidity and mortality in these patients. Patients with CLL and NHL are at higher risk of hospitalization and death from COVID-19.3 Data is lacking regarding the effectiveness of COVID-19 vaccination in this patient population. Objective: Determine antibody (Ab) response rate (RR) to the COVID-19 vaccination in patients with CLL and indolent NHL. Design: A retrospective, observational study of patients seen between January and October 2021. Updated data was collected until May 27, 2022. Setting: Patients followed in a lymphoma clinic at the Robert H. Lurie Comprehensive Cancer Center. Participants: 398 patients were screened for eligibility. Inclusion criteria were confirmed diagnosis of CLL or indolent NHL, completion of a full vaccination series with either Johnson & Johnson, Moderna, or Pfizer, and Ab testing within 6 months of the initial vaccination series. Main Outcome Measures: SARS-CoV-2 Ab titers were obtained after completion of a full vaccination series and, if applicable, after a third vaccine dose. Ab response was considered positive if either total Ab titer or IgG spike protein Ab was positive. Comparisons were performed using chi-square tests. Results: 240 patients were included in the final analysis. Ab response to the initial vaccination series was 50% (91/181) in CLL and 69% (41/59) in other indolent NHLs. For CLL patients, there was a higher Ab RR in patients receiving the Moderna compared to the Pfizer vaccine (61% vs 44%, p=0.028). Current or prior cancer therapy correlated with a lower Ab RR (36% vs 68%, p<0.0001). Use of anti-CD20 agents in the year prior to vaccination resulted in a lower Ab RR (12% vs 53%, p<0.0001). Of the 71 patients with negative Ab response who subsequently received a third vaccine dose, 38% (27/71) developed a measurable Ab response. Conclusions: Ab RR to COVID-19 vaccination is suboptimal in patients with CLL and indolent NHL, and continued infection precautions should be employed. The Moderna vaccine may provide superior humoral immunity to COVID-19 in patients with CLL. A third vaccine dose increases Ab RR in this patient population.